Buzzing RELAY. Please help!

Posted by Sublime_06, Apr 16, 2007
Newbie Forum - Beginner DSM modification questions and discussions. Common, repetitive, and general discussions will get dumped here from other tech forums. Unless you're a Probationary member you shouldn't post threads here.

  1. Sublime_06

    Sublime_06 Proven Member

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    This is my problem.. I have a very annoying buzzing sound coming from the console area.. This only happens when I turn the car to the "OFF" position.

    I have confirmed it NOT to be the ECU. It is coming from a little gold box just to the right of the ECU! When I unplug a relay in the engine compartment labeled "ENGINE" the buzzing stops. Or if I disconnect one of the wiring harnesses in the console area it will also stop.

    I have no idea what is causing this or even what that little gold box is.. Can anyone please help me out. I am at a loss.


    Thanks,
    Chris.
     
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  2. Sublime_06

    Sublime_06 Proven Member

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    After further reading I have concluded that the box making the noise is the EFI, MPI, MFI, ECM, whatever the hell it is called, Relay..

    But what would cause the buzzing noise coming from it?

    Thanks,
    Chris.
     
    #2
  3. luv2rallye

    luv2rallye DSM Wiseman

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    If it's the box with 8 wires, it is the MPI/FP combo relay (2 relays inside - 1 for MPI, 1 for fuel pump). Since it stops when you pull the Engine fuse, it must be the MPI relay that's buzzing (FP is off ignition switch). Either the relay is bad (have to replace whole box) or the ECU is continuously turning it on/off. Could be either. Open up the ECU and check for leaking capacitors (by sight and by fish smell) and/or try a known good relay.

    If you want to test the relay, unplug it and apply +12V (thru a fuse) to pins (4 & 8) of the relay that had the red/black wires on it's connector pin. Then apply ground to pin 6 (blue/green wire on it's connector) and the relay should stay activated (click once and not buzz) as long as the ground is applied. While activated you should get +12V on pins 2 (red) and 3 (black/red).
     
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  4. Sublime_06

    Sublime_06 Proven Member

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    Hey man, thanks for the response. So I just went outside and pulled the relay. I hooked up a +12v to pins 4 and 8, and ground to pin 6. The relay would click on once I applied the ground, and then click off when i released the ground. I was getting +12v on pins 2 and 3. So the relay appears to be fine I suppose.

    I then went to my ECU and pulled the top off.. I dont smell any sort of "fish" smell and nothing appears to be leaking. I have no idea where to look next.

    Any more ideas?

    Thanks,
    Chris.
     
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  5. romeen

    romeen DSM Wiseman

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    My car would not start one day. When I tried to start it the starter relay would buzz but the motor would not crank at all. I replaced the relay with the same result. I finally discovered that the hot cable running from the battery + to the starter had completely broken under the insulation.

    My point is that in my buzzing relay case the relay was fine, the component that it was associated with was fine (the starter and solenoid tested fine), but there was a problem in not being able to deliver power to the starter. Maybe this experience will be helpful and give you some further ideas as far as places to look.

    Good luck.
     
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  6. luv2rallye

    luv2rallye DSM Wiseman

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    With the relay reconnected, first make sure you are getting a full +12V on pins 4 & 8. [Also make sure it's not the FP relay that's buzzing (voltage on pin 7 with key off).] Then check to see if the ECU is the one turning the MPI relay off and on (when you turn key to off) by measuring the voltage on relay pin 6 (or ECU pin 38). If it is toggling between +12 and 0V (or it may read as an average of some non-zero voltage in between these two), the ECU is doing it. You then have to determine if something is telling the ECU to do this or if the ECU itself is bad. Easiest way is to swap ECU with a known good one. Otherwise PM Steve who is the expert on ECU operation. He has a great explanation here on the 1g ECU operation which will give you the basics (2g ECU operation will be similiar but remember 2g ECU has different pinout): http://www.dsmtuners.com/forums/showthread.php?p=151173312#post151172645
     
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  7. Sublime_06

    Sublime_06 Proven Member

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    Quick update before I do all that stuff.. I just noticed this 10 minutes ago. When I engage the e-brake the buzzing stops.. When its dis-engaged it starts buzzing again.

    Any ideas now?
     
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  8. luv2rallye

    luv2rallye DSM Wiseman

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    That's really weird. Was something done on the car recently? When did this start? All I can think of is maybe something is wired wrong or a missing ground (most likely), or a short, or wire broken?
     
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  9. Sublime_06

    Sublime_06 Proven Member

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    The only thing I can think of that is wired into the e-brake is the turbo timer. It's required to be up for it to function. Does the turbo timer tie into any wires and control that relay?

    Thanks,
    Chris.
     
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  10. laserspeeddemon

    laserspeeddemon Proven Member

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    Yes, the turbo timer ties into the ignition harness which in turns controls the rest of the engine control components. Something is not wired right. Sound like there is to much amps going through that relay or it's shorting, which is not as likely.
     
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  11. 2GeNTSi

    2GeNTSi Proven Member

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    Alright I just recently had no-starting issues (used to be no-crank but I wired up a push-button starter) and I just pulled out the relay from my car. I have two alligator clips coming from the positive terminal on my battery to pins 4+8, then one alligator clip from from the negative terminal to pin 6 (then the relay clicked once). I then got a voltmeter and applied them to pins 2+3 but I'm not getting any voltage. I'm assuming it's bad?

    Now the reason I'm doing this is because the car is cranking perfectly but is not firing up, and I USED to be able to hear my FP turn on when putting the key to the ON position. But also I've been driving the car for a few days when I wasn't able to hear the FP. Is this possibe? I've also tested the FP and I was able to hear it when applying power to it directly.
     
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  12. 2GeNTSi

    2GeNTSi Proven Member

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    UPDATE:

    This morning I plugged the relay back in and put the key to the ON position and noticed pin 6 was only outputting 0.53v?? Also while cranking, pin 1 was outputting only 9v at max, I tested it at the other end where the harness hooks up to the FP and it's the same. Pins 4+8 both have 12v and FP powered up fine when directly hooked up to battery.

    I was looking into re-wiring the FP, but I noticed that the new relay would use the MPI pin 1 wire to power it (along with a direct connection to the battery). So in my case this wouldn't work since pin 1 is only putting out 9 volts correct?

    UPDATE AGAIN:

    I tried starting it again (just for the hell of it) and it started up, I tested pin 1 on the relay again and it was now showing 13v, and I could hear the FP but I still don't think it's as loud as it used to be. I shut it off and tried starting it multiple times and it worked. It was doing this earlier in the week where the 1st start-up in the morning would take a few tries but after that the rest of the day would be fine.
     
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  13. 4g63mannvann

    4g63mannvann Probationary Member

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    the best thing to do is check your wiring for any cracks, when relays buzz it usually means high amperage which means there is something not making a good contact. it could be the fuse before it or one of the wires that is cracked. you can usually check that by feeling for heat.
     
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  14. Prodigyman

    Prodigyman Proven Member

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    I just had exact same issue. Read your post and same thing has happed to me. Starter positive wire became loose, causing that sound. Very useful info, thanks.
     
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